High-bandwidth Digital Content Protection (HDCP™) is utilized for digital content protection, providing for encryption of content or data transmitted over digital interfaces, including High-Definition Multimedia Interface (HDMI™) or Mobile High-Definition Link (MHL™). In today's HDCP-protected data stream, an intermediate carrier (also referred to as a “bridge” device) has to employ a complete encryption engine as well as a decryption engine to decrypt the entire data stream (that is encrypted at an upstream transmitting device, also referred to as a “source” device) to measure and process the content of the data stream and further, to re-encrypt the entire data stream before it is sent to the next downstream receiving device (also referred to as a “sink” device). In the HDCP specification, this process is referred to as “repeater”. Having complete encryption and decryption engines at a bridge device is expensive, such as in terms of consuming power and die space, having to assume additional costs for having two complete key sets, requiring additional testing, and the like.
It is contemplated that various signaling protocols (e.g., Original Encryption Status Signaling (OESS), Enhanced Encryption Status Signaling (EESS)) may be used between sources and sinks for providing and detecting encrypted data streams, such as whether encryption of a data stream is enabled or disabled. For example, EESS protocol is used with the HDMI protocol (and is an optional feature in the Digital Visual Interface (DVI™) protocol), while OESS is used with the DVI protocol.